When Moons and Rings Collide

By Nancy Atkinson - November 11, 2008 at 5:21 PM UTC | Planetary Science
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This is absolutely astounding! The Cassini spacecraft captured a collision between Saturn's moon Prometheus and the F ring, which creates a "streamer;" material being pulled from the ring by the moon's gravity, leaving behind a dark channel. There's even a

movie of the event!

The creation of these streamers and channels occurs in a cycle that repeats during each of Prometheus' orbits. During its 14.7 hour orbit of Saturn, when Prometheus reaches apoapse, or where it is farthest away from Saturn and closest to the F ring, the oblong moon draws a streamer of material from the ring. But since Prometheus orbits faster than the material in the ring, this new streamer is pulled from a different location in the ring about 3.2 degrees (in longitude) ahead of the previous one. In this way, a whole series of streamer-channels is created along the F ring, and Cassini has captured more images showing what are called streamer-channels.

New images, as the one below, again look at the streamer-channels. This image looks toward the unilluminated side of the rings from about 36 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 30, 2008. The view was acquired at a distance of approximately 970,000 kilometers (602,000 miles) from Saturn and at a Sun-ring-spacecraft, or phase, angle of 45 degrees. Image scale is 5 kilometers (3 miles) per pixel.

[caption id="attachment_20950" align="alignnone" width="580" caption="Streamers and channels. Credit: NASA/JPL/Space Science Institute""]

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In some observations, 10 to 15 streamer-channels can easily be seen in the F ring at one time (at left). Eventually, a streamer-channel disappears as shearing forces (i.e., Keplerian shear) act to disperse the constituent dust particles.

The movie shows just under half of a complete streamer-channel cycle. The dark frames in the movie represent the period during which Prometheus and the F ring pass through Saturn's shadow. The images in the movie were acquired by the Cassini spacecraft narrow-angle camera on November 23 and 24, 2006. The movie sequence consists of 72 clear spectral filter images taken every 10.5 minutes over a period of about 12.5 hours.

Source:

Cassini

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Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com